ball lightning

Ball lightning is described as a luminous sphere which seems to appear
out of nowhere and vanish into thin air. It varies in size from two to ten
inches in diameter. It usually is seen shortly before or after, or during,
a thunderstorm. Its duration varies from a few seconds to a few minutes.
"The lifetime of ball lightning tends to increase with size and
decrease with brightness. Balls that appear distinctly orange and blue
seem to last longer than average....Ball lightning usually moves parallel
to the earth, but it takes vertical jumps. Sometimes it descends from the
clouds, other times it suddenly materializes either indoors or outdoors or
enters a room through a closed or open window, through thin nonmetallic
walls or through the chimney."*

Some have speculated that ball lightning is a plasma ball, but that
theory has been dismissed because a "hot globe of plasma should rise
like a hot-air balloon" and that is not what ball lightning does.
Many physicists have speculated
that ball lightning must be due to electrical discharges. For example,
Russian physicist
Pyotr Kapitsa
described ball lightning as an electrodeless
discharge caused by a standing UHF waves of unknown origin present between
the earth and a cloud.*
According to another theory, "outdoor ball lightning is caused by an
atmospheric maser-- analogous to a laser, but operating at a much lower
energy--having a volume of the order of many cubic kilometers."*

Two New Zealand scientists, John Abrahamson and James Dinniss, believe
ball lightning consists of "fluffy balls of burning silicon created
by ordinary fork lightning striking the earth."

According to their theory, when lightning strikes the ground, the minerals
are broken down into tiny particles of silicon and its compounds with
oxygen and carbon. The tiny charged particles link up into chains, which
go on to form filamentary networks. These cluster together in a light
fluffy ball, which is borne aloft by air currents. There, it hovers as
ball lightning, or a burning orb of fluffy silicon emitting the energy
absorbed from the lightning in form of heat and light, until the
phenomenon burns itself out.*

Ball lightning has been observed since ancient times and by thousands
of people in many different places. Most physicists seem to believe that
there is little doubt that it is a real phenomenon. But there is still
disagreement as to what it is and what causes it.